• 한국자기학회지
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• 제17권2호
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• pp.55-59
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• 2007

본 논문에서는 Co를 주성분으로 하는 아몰퍼스 자성 와이어를 동축케이블의 신호선으로 하는 자계센서를 제작하여 외부자계에 대한 특성을 측정하였다. 측정된 임피던스의 주파수의존성에는 전송선로의 공진특성이 반영되었으며 인가자계가 없을 때, 1/4 파장에 해당하는 주파수가 250 MHz에서 나타났다. 측정 주파수대역에서는 표피효과에 의한 저항성분이 임피던스를 거의 결정하였으며 또한 외부자계가 $0\;Oe{\sim}1\;Oe$ 사이에서 임피던스는 자성 아몰퍼스와이어의 투자율의 변화에 의해 크게 변화하였다. 0.1 Oe 부근에서 150 MHz의 ${\Delta}Z/{\Delta}H$가 $300{\Omega}/Oe$이라는 매우 큰 값이 얻어져 Co를 주성분으로 하는 자성와이어를 동축케이블형 자계센서로 사용하는 경우 센서로서 매우 유용함을 알 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.501-502
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• 2011

Based on the several advantages of high-temperature superconducting cable, there are many researches about HTS cable. In the aspect of power system engineering, since it has very low impedance, approximately zero, it is profitable for large capacity distribution line into the large scale load. In the step of its verifications, the HTS cable had been installed in Icheon substation and operated. In this paper, the protection coordination for Icheon substation had been designed and verified using PSCAD/EMTDC.

• 대한전기학회논문지:전력기술부문A
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• 제53권1호
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• pp.13-21
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• 2004

In the design of superconducting cable systems, quench analysis have to be advanced for applying to a real systems. It is necessary to calculate the current, voltage and resistance during the quench. Simulation program named EMTDC was used to analyze the quench state. Normal zone evaluation and quench development with EMTDC are one of the major features of quench analysis. This paper presents the two kinds of quench control models which are the Switch Control Type and the Fortran Control Type. In case of the quench developing area, the simplicity cable model consist of resistance, inductance and capacitance. The impedance of the pipe type superconducting cable is calculated by numerical analysis method. The resistance and inductance increased during quench. However the variation have an effect on the fault current. The voltage was also developed by resistance and inductance. This paper presents the relationship between the current. voltage, resistance and inductance during quench.

• 대한전기학회논문지:전력기술부문A
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• 제52권12호
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• pp.713-721
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• 2003

This paper analyzes the switching overvoltage occurred on 345kV underground power cable system as well as combined transmission system using EMTP. Cable length and closing time, preinsertion resistance have effect on switching overvoltage. Therefore, this paper analyzes the switching overvoltage occurred on conductor and sheath with change of those parameters. Specially, the cross bonding position becomes discontinuity point because of the difference between surge impedance of metal sheath and that of lead cable. Thus, the transmission and the reflection of traveling wave complexly occur at this connection point. According to these influences, voltage between sheath and earth as well as voltage between joint boxes rise. Time to crest point of switching overvoltage is longer than lightning overvoltage. Even though the voltage induced by switching surge is smaller than lightning surge, that voltage may have serious effect on the metal sheath. Therefore, this paper also analyses the reduction effect of switching overvoltage when the preinsertion resistance of circuit breaker is considered.

• 한국자동차공학회논문집
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• 제21권2호
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• pp.159-165
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• 2013

ESD damage by Charged Cable Model (CCM) is introduced. Due to its own impedance characteristic unlike Human Body Model (HBM) or Machine Model (MM) electric component can be destroyed even though it is located after typical protection circuit. Possible mechanism of ESD damage to automotive electric control unit (ECU) in vehicle environment by CCM discharge was investigated. Based on investigation, field-returned vehicle whose ECU is expected to be damaged by CCM discharge was tested to reproduce it and similar electric component destruction inside ECU was observed. Suggestions to reduce the possibility of ESD damage by CCM are introduced.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.412-414
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• 2004

In this paper, a novel algorithm of underground cable fault location based on the analysis of distributed parameter circuit is proposed. The proposed method makes voltage and current equations about core and sheath, and then establishes a function of the fault distance according to the analysis of fault conditions. Finally gets the solution of this function through Newton-Raphson iteration method. The effectiveness of proposed algorithm has been verified by Matlab program, and the cable parameters such as impedance and admittance are from EMTP simulation.

• Structural Engineering and Mechanics
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• 제55권6호
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• pp.1261-1278
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• 2015

Due to their low intrinsic damping, stay cables in cable-stayed bridges have often exhibited unanticipated and excessive vibrations which result in increasing maintenance frequency and disruption to normal operations of the entire bridges. Mitigation of undesired cable vibration can be achieved by attaching an external damping device near the anchorage. High Damping Rubber (HDR) dampers have many advantages such as compact size, better aesthetics, easy maintenance, temperature stability, and cost benefits; therefore, they have been widely used to increase cable damping. Although a single damper has been shown to reduce cable vibrations, it is not the most effective method due to geometric constraints. This paper proposes the use of two HDR dampers to improve effectiveness and robustness in suppressing cable vibration. Oscillation parameters of the cable-dampers system were investigated in detail by modeling the stay cable as a taut string and each HDR damper as complex-valued impedance and by using an analytical formulation of the complex eigenvalue problem. The problem of two HDR dampers arbitrarily located along a cable is solved and the solution is discussed. Asymptotic formulas to calculate the damping ratios of the cable with two HDR dampers installed near the anchorage(s) are proposed and compared with the exact solutions. Further, a design example is presented in order to justify the methodology. The results of this study show that when the two HDR dampers are installed close to each other on the same end of the cable, some interaction between the dampers leads to reduced damping ratio. When the dampers are on the opposite ends of the cable, they are effective in increasing damping ratio and can provide better vibration reduction to multiple modes.

• 전기학회논문지
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• 제57권2호
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• pp.172-178
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• 2008

If the fault occurs on the underground power cable systems, the fault current on the sheath has an influence on all sections of cable because it's returned through earth at the directly grounded point and operation point of SVL(Sheath Voltage Limiter) on each insulated joint box. Therefore, the earth resistance and the operation of SVL have an effect on the zero-sequence current, and then the impedance between relaying point and fault point is increased. That causes the overreach of distance relay. For these reasons, the distance relay algorithm for protecting an underground power cable systems hasn't been developed till now. In this paper, new distance relay algorithm is developed for protecting a underground power cable system using fuzzy inference system which is the one of ACI(Advanced Computational Intelligence) techniques. This algorithm is verified by EMTP simulation of real power cable system, and proves to effectively advance the errors

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
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• pp.29-33
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• 2001

Sheath circulating current results from the change of sheath mutual impedance which is caused by unbalanced cable system, and different section length between joint boxes. If circulating over current flows in sheath, it produces much sheath loss which reduces the transmission capacity. And also such large sheath current influences severely on the operator. Recently, large sheath circulating current was partially measured in underground cable system of KEPCO. Accordingly, actual schemes to reduce sheath circulating over current is urgently required for installed cable system as well as newly-constructing cable system. This paper describes the analysis of sheath circulating current and various schemes to reduce the large circulating current in case of operating cable system using EMTP/ATPDraw. And also, possible schemes are proposed through a detailed analysis regarding cable systems by considering various electrical and environmental factors. It is evaluated that the proposed reduction schemes can be effectively applied to reduce the large sheath circulating over current with the minimized electrical problems.

• JSTS:Journal of Semiconductor Technology and Science
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• 제13권5호
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• pp.423-429
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• 2013

A 6-Gb/s differential voltage mode driver is presented whose output impedance and pre-emphasis level can be controlled independently. The voltage mode driver consists of five binary-weighted slices each of which has four sub-drivers. The output impedance is controlled by the number of enabled slices while the pre-emphasis level is determined by how many sub-drivers in the enabled slices are driven by post-cursor input. A prototype transmitter with a voltage-mode driver implemented in a 65-nm CMOS logic process consumes 34.8-mW from a 1.2-V power supply and its pre-emphasized output signal shows 165-mVpp,diff and 0.56-UI eye opening at the end of a cable with 10-dB loss at 3-GHz.